Update XZ Utils to 5.0.4 (third_party)

doc/examples/02_decompress.c

+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       02_decompress.c
+/// \brief      Decompress .xz files to stdout
+///
+/// Usage:      ./02_decompress INPUT_FILES... > OUTFILE
+///
+/// Example:    ./02_decompress foo.xz bar.xz > foobar
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <lzma.h>
+
+
+static bool
+init_decoder(lzma_stream *strm)
+{
+        // Initialize a .xz decoder. The decoder supports a memory usage limit
+        // and a set of flags.
+        //
+        // The memory usage of the decompressor depends on the settings used
+        // to compress a .xz file. It can vary from less than a megabyte to
+        // a few gigabytes, but in practice (at least for now) it rarely
+        // exceeds 65 MiB because that's how much memory is required to
+        // decompress files created with "xz -9". Settings requiring more
+        // memory take extra effort to use and don't (at least for now)
+        // provide significantly better compression in most cases.
+        //
+        // Memory usage limit is useful if it is important that the
+        // decompressor won't consume gigabytes of memory. The need
+        // for limiting depends on the application. In this example,
+        // no memory usage limiting is used. This is done by setting
+        // the limit to UINT64_MAX.
+        //
+        // The .xz format allows concatenating compressed files as is:
+        //
+        //     echo foo | xz > foobar.xz
+        //     echo bar | xz >> foobar.xz
+        //
+        // When decompressing normal standalone .xz files, LZMA_CONCATENATED
+        // should always be used to support decompression of concatenated
+        // .xz files. If LZMA_CONCATENATED isn't used, the decoder will stop
+        // after the first .xz stream. This can be useful when .xz data has
+        // been embedded inside another file format.
+        //
+        // Flags other than LZMA_CONCATENATED are supported too, and can
+        // be combined with bitwise-or. See lzma/container.h
+        // (src/liblzma/api/lzma/container.h in the source package or e.g.
+        // /usr/include/lzma/container.h depending on the install prefix)
+        // for details.
+        lzma_ret ret = lzma_stream_decoder(
+                        strm, UINT64_MAX, LZMA_CONCATENATED);
+
+        // Return successfully if the initialization went fine.
+        if (ret == LZMA_OK)
+                return true;
+
+        // Something went wrong. The possible errors are documented in
+        // lzma/container.h (src/liblzma/api/lzma/container.h in the source
+        // package or e.g. /usr/include/lzma/container.h depending on the
+        // install prefix).
+        //
+        // Note that LZMA_MEMLIMIT_ERROR is never possible here. If you
+        // specify a very tiny limit, the error will be delayed until
+        // the first headers have been parsed by a call to lzma_code().
+        const char *msg;
+        switch (ret) {
+        case LZMA_MEM_ERROR:
+                msg = "Memory allocation failed";
+                break;
+
+        case LZMA_OPTIONS_ERROR:
+                msg = "Unsupported decompressor flags";
+                break;
+
+        default:
+                // This is most likely LZMA_PROG_ERROR indicating a bug in
+                // this program or in liblzma. It is inconvenient to have a
+                // separate error message for errors that should be impossible
+                // to occur, but knowing the error code is important for
+                // debugging. That's why it is good to print the error code
+                // at least when there is no good error message to show.
+                msg = "Unknown error, possibly a bug";
+                break;
+        }
+
+        fprintf(stderr, "Error initializing the decoder: %s (error code %u)\n",
+                        msg, ret);
+        return false;
+}
+
+
+static bool
+decompress(lzma_stream *strm, const char *inname, FILE *infile, FILE *outfile)
+{
+        // When LZMA_CONCATENATED flag was used when initializing the decoder,
+        // we need to tell lzma_code() when there will be no more input.
+        // This is done by setting action to LZMA_FINISH instead of LZMA_RUN
+        // in the same way as it is done when encoding.
+        //
+        // When LZMA_CONCATENATED isn't used, there is no need to use
+        // LZMA_FINISH to tell when all the input has been read, but it
+        // is still OK to use it if you want. When LZMA_CONCATENATED isn't
+        // used, the decoder will stop after the first .xz stream. In that
+        // case some unused data may be left in strm->next_in.
+        lzma_action action = LZMA_RUN;
+
+        uint8_t inbuf[BUFSIZ];
+        uint8_t outbuf[BUFSIZ];
+
+        strm->next_in = NULL;
+        strm->avail_in = 0;
+        strm->next_out = outbuf;
+        strm->avail_out = sizeof(outbuf);
+
+        while (true) {
+                if (strm->avail_in == 0 && !feof(infile)) {
+                        strm->next_in = inbuf;
+                        strm->avail_in = fread(inbuf, 1, sizeof(inbuf),
+                                        infile);
+
+                        if (ferror(infile)) {
+                                fprintf(stderr, "%s: Read error: %s\n",
+                                                inname, strerror(errno));
+                                return false;
+                        }
+
+                        // Once the end of the input file has been reached,
+                        // we need to tell lzma_code() that no more input
+                        // will be coming. As said before, this isn't required
+                        // if the LZMA_CONATENATED flag isn't used when
+                        // initializing the decoder.
+                        if (feof(infile))
+                                action = LZMA_FINISH;
+                }
+
+                lzma_ret ret = lzma_code(strm, action);
+
+                if (strm->avail_out == 0 || ret == LZMA_STREAM_END) {
+                        size_t write_size = sizeof(outbuf) - strm->avail_out;
+
+                        if (fwrite(outbuf, 1, write_size, outfile)
+                                        != write_size) {
+                                fprintf(stderr, "Write error: %s\n",
+                                                strerror(errno));
+                                return false;
+                        }
+
+                        strm->next_out = outbuf;
+                        strm->avail_out = sizeof(outbuf);
+                }
+
+                if (ret != LZMA_OK) {
+                        // Once everything has been decoded successfully, the
+                        // return value of lzma_code() will be LZMA_STREAM_END.
+                        //
+                        // It is important to check for LZMA_STREAM_END. Do not
+                        // assume that getting ret != LZMA_OK would mean that
+                        // everything has gone well or that when you aren't
+                        // getting more output it must have successfully
+                        // decoded everything.
+                        if (ret == LZMA_STREAM_END)
+                                return true;
+
+                        // It's not LZMA_OK nor LZMA_STREAM_END,
+                        // so it must be an error code. See lzma/base.h
+                        // (src/liblzma/api/lzma/base.h in the source package
+                        // or e.g. /usr/include/lzma/base.h depending on the
+                        // install prefix) for the list and documentation of
+                        // possible values. Many values listen in lzma_ret
+                        // enumeration aren't possible in this example, but
+                        // can be made possible by enabling memory usage limit
+                        // or adding flags to the decoder initialization.
+                        const char *msg;
+                        switch (ret) {
+                        case LZMA_MEM_ERROR:
+                                msg = "Memory allocation failed";
+                                break;
+
+                        case LZMA_FORMAT_ERROR:
+                                // .xz magic bytes weren't found.
+                                msg = "The input is not in the .xz format";
+                                break;
+
+                        case LZMA_OPTIONS_ERROR:
+                                // For example, the headers specify a filter
+                                // that isn't supported by this liblzma
+                                // version (or it hasn't been enabled when
+                                // building liblzma, but no-one sane does
+                                // that unless building liblzma for an
+                                // embedded system). Upgrading to a newer
+                                // liblzma might help.
+                                //
+                                // Note that it is unlikely that the file has
+                                // accidentally became corrupt if you get this
+                                // error. The integrity of the .xz headers is
+                                // always verified with a CRC32, so
+                                // unintentionally corrupt files can be
+                                // distinguished from unsupported files.
+                                msg = "Unsupported compression options";
+                                break;
+
+                        case LZMA_DATA_ERROR:
+                                msg = "Compressed file is corrupt";
+                                break;
+
+                        case LZMA_BUF_ERROR:
+                                // Typically this error means that a valid
+                                // file has got truncated, but it might also
+                                // be a damaged part in the file that makes
+                                // the decoder think the file is truncated.
+                                // If you prefer, you can use the same error
+                                // message for this as for LZMA_DATA_ERROR.
+                                msg = "Compressed file is truncated or "
+                                                "otherwise corrupt";
+                                break;
+
+                        default:
+                                // This is most likely LZMA_PROG_ERROR.
+                                msg = "Unknown error, possibly a bug";
+                                break;
+                        }
+
+                        fprintf(stderr, "%s: Decoder error: "
+                                        "%s (error code %u)\n",
+                                        inname, msg, ret);
+                        return false;
+                }
+        }
+}
+
+
+extern int
+main(int argc, char **argv)
+{
+        if (argc <= 1) {
+                fprintf(stderr, "Usage: %s FILES...\n", argv[0]);
+                return EXIT_FAILURE;
+        }
+
+        lzma_stream strm = LZMA_STREAM_INIT;
+
+        bool success = true;
+
+        // Try to decompress all files.
+        for (int i = 1; i < argc; ++i) {
+                if (!init_decoder(&strm)) {
+                        // Decoder initialization failed. There's no point
+                        // to retry it so we need to exit.
+                        success = false;
+                        break;
+                }
+
+                FILE *infile = fopen(argv[i], "rb");
+
+                if (infile == NULL) {
+                        fprintf(stderr, "%s: Error opening the "
+                                        "input file: %s\n",
+                                        argv[i], strerror(errno));
+                        success = false;
+                } else {
+                        success &= decompress(&strm, argv[i], infile, stdout);
+                        fclose(infile);
+                }
+        }
+
+        // Free the memory allocated for the decoder. This only needs to be
+        // done after the last file.
+        lzma_end(&strm);
+
+        if (fclose(stdout)) {
+                fprintf(stderr, "Write error: %s\n", strerror(errno));
+                success = false;
+        }
+
+        return success ? EXIT_SUCCESS : EXIT_FAILURE;
+}